Lifting truck



H. E. SPENCER.

LIFTING TRUCK.

APPLICATIN FILED APR.12. 1920.

Patented Jan. 17, 1922.

2 SHEETS-SHEET l.

H. E. SPENCER.

LIFTING TRUCK.

APPLlcAmN FILED APR,12.1920.

Patented' Jan. 17 ,1922.

2 SHEETS-SHEET 2.

UNITED STATES PATENT QFTICE.

HAROLD EDWIN SPENCER, 0F GRAVESEND, ENGLAND, ASSIGNOR TO HESCO LIMITED,

OF LONDON,

ENGLAND.

LIFTING TRUCK.

Application led April 12,

To all whom zit may concern.'

Be it known that I, HAROLD EDWIN SPEN- GER, subject of the King ofEngland, residing at Gravesend,` in the county of Kent, England, haveinvented certain new and useful Improvements in Lifting Trucks, of whichthe following is a specification.

This invention is for improvements in or relating to lifting-trucks;that is to say to trucks whereof one part can be raised and loweredrelatively to another part in order to permit the truck to be run underaload, the movable part of the truck raised to lift the load clear of theground and the load then transported on the truck in such raisedposition. Subsequently by lowering the movable part of the truck theload can be deposited on the ground again and the truck drawn out Jfromunder it.

The invention relates to lifting-trucks of the type in which a pawloperating between two parts, one of which moves relatively to the otherduring the raising and lowering of the truck, is employed to retain themovable part in its position corresponding to the raised position of thetruck, when desired.

In certain lifting-trucks of this type as hereinbefore constructed aspring is provided which automatically releases the pawl when thedraught handle of the truck is actuated to take the weight of the-loadoflI the pawl, this spring' always tending' to pull the pawl out ofoperative position when the truclr is in its raised position. Thisconstant tendency to render the pawl inoperative is objectionable fromsome points of view, particularly when the various parts of themechanism become somewhat worn or out of correct adjustment es abnormaljolt- Specification of Letters Patent.

1920. Serial No. 373,356.

.Other objects of the invention are to provide a more' effective andreliable locking mechanism for lifting-trucks than has heretofore beenavailable, and to provide a construction which shall be simple in designand easy to manufacture.

The primary feature of the present invention consists in a lifting-truckof the type above described which is characterized in that the pawl isprovided with a controlling and withdrawal device (for example a lever)operatively connected through yield` ing means (for example a spring) tothe pawl, and in that abutments are provided on the truck to limit themovement of the said controlling and withdrawal device in two positions(for example two angular positions of a lever about its pivot) in oneonly of which the relative positions of the controlling device and pawlare such that the controlling device, through the yielding meansconnecting it to the pawl, applies withdrawal force to the latter totend to withdraw it from operative position, the normal mode of bringingsaid controlling device into pawl-withdrawing position being manual andindependent of the liftingmechanism of the truck, and the normalposition occupied by said controlling device during travel of the truckboth in its lowered and raised positions being that'in which thecontrolling device is not applying withdrawal force to the pawl.

This and other features of the invention will be fully described andindicated in the following speciiication and its appended claims.

There will now be described, by way of example only, certainconstructional forms of lifting-truck according to the invention. It isto be understood that the inr-.f'ention is not limited to the precisedetails of construction enumerated.

In the drawings- Y Figure 1 is a side elevation partly in section of alifting-truck7 the parts thereof with which the present invention ismore particularly concerned being shown in full or dotted lines, whilethe remainder of the truck is shown in chain lines. In this ligure thetruck is shown with its' frame 10W- ered.

Figure 2 is a corresponding partial view Patented Jan. 17, 1922. e

with the parts in the position they occupy When the frame is raised, andwhen the controlling and Withdrawal lever has been set intopaivl-Withdraiving position.

Figure 3 is a plan corresponding to Figure 1.

Figure is a view somewhat similar to Figure 2, but showing the parts inthe position they occupy near the eoniniencei'nent of the operation oflowering the trarne.

Figure 5 is a view correspondingto a portion of Figure l showing amodified construction of truck.

Figure 6 is a vieiv corresponding to Figure 2 of the construction shownin Figure Figure 7 is a view corresponding to Figure 4 of theconstruction shown in Figure 5, and

Figure 8 is a detail view on a larger seele.

Like letters of reference indicate like parts throughout the drawings.

f Referring firstly to Figures l to e, the lifting-truck illustrated 1soil the kind described in my United Iintates specification No.

373,355 and comprises a 'traine A mounted upon two pairs of wheels B and(l by bellcrank levers D and a cross-member F connected to the' levers Dby bars E. One end of each bell-crank lever is niounted on the axle otthe Wheels C, and lintermediate its Vends each bell-crank lever ismounted on the frame A. The cross-member F pivoted in the frame A ateach side. Piveted in the cross-member F on a pivot G is an element H,carrying another pivot J on which is mounted a steering head K. TheWheels B are the steering wheels ol the truck7 and the steering head Knieves with the axle L of these steering Wheels, The draught handle M byineens o'lE a pin and slot connection with the steering` head l may becoupled to the cross-ineinbei` F to rotate the sanie'about the axle L toraise or lower the frame A, all as described in iny aforesaidspecification No. 373,355.

When the cross-member F and its connected parts have been brought intothe raised position of the frame, see Figure 2, it is necessary toprovide means for preventing undesired rotation of the parts diie togravity. For this purpose a paivl N is provided. This paivl is pivotedat NL upon thc traine A and its end N2 is arranged in the path of aprojection F4 on the cross-member F. Adjacent the projection F* is aledge F5 upon which the end of the paivl may rest while in engagementwith the projection FH Also pivoted on the frame A is a controlling andWithdrawal lever O, its pivot being designated O1. This lever O isconnected to the pawl N by'studs O2 and N3 respectively being coupled byyielding' means which in the construction illustrated take the vforni ota spring P, and the lever is arranged to bear against a stop pin Q onthe fraine A when the parts are in the position shown in Figure l.Adjacent the projectionF4 the cressn'iernber F is provided with. a cuniF6 agai'int which7 when the parts are in the A position shown in Figure2, 'the stud @2 will bear.

The operation may be described as tolloivs:-ltlhen the parts are in theposition shoivn in Figure l, the spring F is oit such length as 'tosustain the pavvl N in a position With its end N2 slightly lower thanthat it occupies When in operative position resting on the ledge andenga-ging the projection F4. ,its the cross-member F is rotated about'the axle L to bring it into the 1 position shown in Figure 2 namelywith the traine raised7 the projection Will pass under the paivl hl andalloiv the latter to `itall by gravity behind it into operativeposition. The paivl N in this position will. prevent undesired rotationet the crossincinber F duc to gravity, and it Will be seen that in thisposition the paivl is not in withdraw it from operative position. ltdesired the end N2 may be shaped to corre-V spout.t to a slightiindercuttiiig of the projection FL to provide a certain amount of retance to Withdrawal.

lt will be seen 'troni Figures 1 and 2 that the controlling andWithdrawal lever 0 has tivo operative angular positions. lts function inone et these, nainely that shown in Figure l., has just been describedit nierely sustainin the paivl hl in position to fall into lockingengageinentwvith the projection Fc as the latter is rotated under it.lits other position. namely that shown in. Figure 2, is itspaivl-ivithdraiving position. The lever (l is nioved into this positioninanually when it is desired to release the pawl prior to lowering' theframe il. Referring to Figure il it will be seen that when the lever isin its paivl-ivithdraiving position, with its stud @E bearing againstthe cani surface F6, the spring is detornried viz. stretched in thearrangement illustratech and in addition to tendin to Withdraw ,thepaivl N willV operate to retain the lever O in this position. rllhisoccurs owing to the relative positions ot the pivot N1 and 01. andolithe studs N3 and U2. The leverthereiiore when once it has been placed inpavvl-ivithdraiving positie will reina-in there, even atte-r Withdr.inn` the pawl, until automatically returned to its other position asivillbe hereinater described.

llo effect the lowering of the traine ,er utter the lever O has beenbrought into its pand-ivithdraiving position it is next necessary torotate the cross-member F in the traine-raising' direction beyond thepoint at which the paivl N (zo-operates With it to prevent undesiredVrotation due to gravity. This extra rotation of the cross-member F iseffected by the draught handle, and has ir the influence et any Ytorcetending to Sti izo

the result first ot taking the weight of the oiii the naw 'n the1position shown operate to d avi the y ligure l quite automaticonsequenupon the rotation oi the mii-er O reaches 'on shown in jioure l, thepawl N vill also fall into the i ition shown in that i'inure and thus hein L e ready to engage projection vhen @Xt the cross-memher F is rotatedto, aise ne iframe A.

instead of the controlling; n l withdravv-*alih device taking' the formo rand-operated lever as in Figures l t 4f, lever may formed suitablyfor toot operation. A construction embodying this principle isillustrated in Figures to 8. This modified construction of truck alsoprovides that when the rontroliino and withdr `wavl-fhexif'e is in itspawl-withdrawing posi-ion it may project into tie path oif a movablepart orn the truck, other than the pivoted cross-member F as describedin connection with Figures to s, so that in the frame-lowering moveentit will automatically he moved trom its pawl-withdrawing positiontov-.Yards its Y Josition.

1 l the C2 to whieh one end or the spring; is connected` similarly tothe l. id lever 0 in Fig;- ures l/to rlie lever has an extended crown T1which may conveniently he serrated to atlord a foothold. The operationot the lever T is similar to that oi" the lever its crown'and hecontinued hy the. couplinghar coming` into Contact with the crown lduring the trame-lowering operation. Jr instead of the pi i-withdrawingposition of the lever heil/n;` determined hy oontact between it and the"iss-member, this position may he determined-hy Contact loetween aprojection, such as the crown T1, on the lever and the coupling har F.rl`he desired operation may ,also e secured in other ways by employing'other parts et the truelr to form the required abutment and to give therequired return movement, rllhe controlling and withdrawal oeviee mightalso so arranged that its own weight assists its return.

lt will be se n from the 'foregoing description that the pawl Niscleared when the truclr is heine; raised so that it may :tall intolocking position the right moment; in such locking; position it is tree.trom stress tending,` to release it, and the'toroe necessary to releaseit need only he applied when release is required. Further, that therelease will only Occur when the weight of the load is taken eti theVlocking mechanism, as although the controlling1 and withdrawaldevice mayhe in pawl-withdrawing position, the pawl will not he withdrawn untilthe load has been thus removed from the locking mechanism. When this isdone, however, not only may the truck he lowered, but the lockingmechanism is automatically returned to the position in which it is readyto operate afresh.

lt will he appreciated that the locking mechanism accordingN to thepresent invention may he applied to constructions ot lifting-truck otherthan are described in my Specification No. 373,355 aforesaid.

rlhe invention is not limited to the precise details or" constructionhereinoefore described, since these may he modified without departingfrom thevspirit and scope of the invention.

lllhat l claim my invention and desire to secure hy Letters Patent islifting-truck comprising two truck iarts, lifting mechanism for movingone Lart relatively to the other to raise and lower the truck, a pawloperating between the two truck parts to retain the movable part in itsposition corresponding' to the raised position of the truck, whendesired, a controlling` and withdrawal device for the pawi, yieldingmeans for connecting said Adevice to the pawhand ahutments on the truckto limit the movement oithe controlling dei/*ice in two positions in oneonly of which the relative positions ot the controllino,- device andpawl are such that the controlling' device, through the yielding meansconnecting` it to the pawl, applies withdrawal torce to the latter totend to withdraw it from operative position the normal Inode of bringingsaid controlling device into pawl-withdrawing position being manual andindependent of the lifting mechanism ot the truck, and the normalposition occupied by said controlling device during travel of the truckboth in its lowered and raised positions being that in which thecontrolling device is not applying withdrawal force to the pawl.

2. A lifting-truck comprising two truck parts, lifting mechanism 'formoving one part relatively to the other to raise and lowerV the truck, apawl operating between the two truck parts to retain the movable part inits position corresponding to the raised position of the truck, whendesired, a controlling and withdrawal lever for the pawl, a pivot forsaid lever, a spring for connecting said lever to the pawl, andabutments on the truck to limit the .movement of the said lever in twoangular positions about its pivot in one only of which the relativepositions oi the lever andpawl are such that the lever, through thespring connecting it tothe pawl, applies withdrawal force to the latterto tend to withdraw it from operative position,` the normal mode oi'bringing said lever into pawlfwithdrawinor position being manual andindependent or the lifting mechanism ot the truck, and the normalposition occupied by said lever dur ing travel of the truck both in itslowered and raised positions being `that, in which the lever is notapplying withdrawal torce to the pawl.

3. A lifting-truck comprising two truck parts, mechanism for moving onepart relatively to the other to raise and lower the truck, a pawloperating between the two truck parts to retain the movable part in itsposition corresponding' to the raised posi- .tion of the truck, whendesired, a controlling and withdrawal device :tor the pawl, yieldingmeans for connecting said device to the pawl, abutments on the truck tolimit the movement of the controlling device in two positions in oneonly of which the relative positions of the controlling device and pawlare such that the controlling device, through the yielding meansconnecting it to the pawl, applies withdrawal torce to the latter totend to withdraw it from operative position, and automatic means formoving the said controlling device from its pawl-with drawing positiontowards its other position during the opera-tion ot lowering the truck.

4. A lifting-truck comprising two truck parts, mechanism `for moving onepart rela tively to the other to raise and lower the truck, a pawloperating between the two truck parts to retain the movable part in itsposition corresponding' to the raised position of the truck, whendesired, a controlling and withdrawal device for the pawl, 'yieldingmeans ior connecting said device to the pawl, and abutments on the truckto limit the movement oi the controlling device in two positions in oneonly of which the relative positions ot the controlling device and pawlare such that the controlling device, through the yielding meansconnecting it to the pawl., applies withdrawal torce to the latter to'tend to withdraw it trom operative position, said controlling devicewhen in its powl-withdrawing position projecting into the path oi a partot' the truck which moves during the lowering operation of the'truclr,whereby lthe said controlling device is automatically moved from itspawl-withdrawing position towards its other position by the said part ofthe truck during the operation of lowering` the truck.

5. A lifting-truck comprising two truck parts, mechanism i'or moving onepart relativ-ly to the other to raise and lower the truck, a pawloperating between the two truck parts to retain the movable part in itsposition corresponding to the raised position ot the truck, whendesired7 a controlling and withdrmval device for the pawl, supports :forsaid device, a pivot for said pawl, a spring connecting said controllingdevice to the pawl, and abutments on the truck to limit the movement ofthe said controlling device in two positions in one only ot which therelative positions of the pivot point ot' the pawl, the supports for thecontrolling device, and the points at which the pawl and controllingdevice are connected by the spring, are such that-(a) the spring tendsto rotate the pawl in the disengaging direction, and (b) the springtends to retain the controlling device in pawl-withdrawing position bothbetore and after the pawl has been' rotated into inoperative position.

6. ric lifting-truck comprising two truck parts, mechanism :tor movingone part rela tively to the other to raise and lower the truck, a pawloperating between the two truck parts to retain the movable part in itsposition corresponding to the raised position et the truck, whendesired, a controlling and withdrawal device for the pawl, supports forsaid device, a pivot for said pawl, a spring connecting said controllingdevice to the pawl, abutments on the truck whereby the movement of thesaid controlling device is limited in two positions in one only of whichthe relative positions et the pivot point of the pawl, the supports forthe controlling device an d the points at which the pawl and controllingdevice are connected by the spring, are such that-(a) the spring tendsto rotate the pawl in the disengaging4 direction, and (o) the springtends to retainthe controlling device in pawl-withdrawing position bothbefore and after the pawl has been rotated into inoperative position,and

automatic ineens for moving the said controlling device from itspaid-withdrawingposition towards its nher posit-ion during 'theoperation oi' ioweiing the truck.

7. A lifting-truck comprising ivc tiuck penis, ineciianisni foi moving`one part reizitiveiy te the other to reise and lower the truck, a p-iiviopeiating between 'che two tinck pers to retain the nioveoie nat in its.L position corresponding "so die mise@L `position of the truck, whendesired, a. conioiiing and wi'iidiavvai device for the pawi suppotsiioi' seid device :i pivot for said pmvi, i spiing connecting saidconti'oiiino' device to the puwi, end zik/nements on che truck iv"ei'ebv the movement of Lne said controlling device is linii'ed in Wopositions in one oniy ci which the relative positions of the pivotpointV oil the pawi, the supports for the conpewi and contioiiing deviceare connected by the spinne, ziije such that-() the spring ienffis torotaie Ehe pewi in 'the disengaging direction, end (ZJ) ie spring tendsto retain .e Contfoliing device in pEvvi-ivithdmvving eosiion boii oeoieansi eilte?, the pawi has been 'roi-ated' ino inopeiaive.positionj oneof said nienniens being cani-simpa?. sind cooperating ,vi ii theeonfcroiiing device during` the icvveiing operation of the truck t0nieve i'iie soie 1evice a suiiiciene4 dismnce out chewing posi'ion as toenable the springv of the conoiiing device ao eeinplee the ienrn oi thedevice to its other oilieietive posiiion. Y

testimony whereof l eiii; my signature.

HAROLD EDWIN SPENCER.

